mirror of https://github.com/rust-lang/rust.git
864eba9fb1
debuginfo: Set bitwidth appropriately in enum variant tags Previously, we unconditionally set the bitwidth to 128-bits, the largest an enum would possibly be. Then, LLVM would cut down the constant by chopping off leading zeroes before emitting the DWARF. LLVM only supported 64-bit enumerators, so this would also have occasionally resulted in truncated data. LLVM added support for 128-bit enumerators in llvm/llvm-project#125578 That patchset trusts the constant to describe how wide the variant tag is, so the high 64-bits of zeros are considered potentially load-bearing. As a result, we went from emitting tags that looked like: DW_AT_discr_value (0xfe) (because `dwarf::BestForm` selected `data1`) to emitting tags that looked like: DW_AT_discr_value (<0x10> fe ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ) This makes the `DW_AT_discr_value` encode at the bitwidth of the tag, which: 1. Is probably closer to our intentions in terms of describing the data. 2. Doesn't invoke the 128-bit support which may not be supported by all debuggers / downstream tools. 3. Will result in smaller debug information. |
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| .. | ||
| enum-bounds-check-derived-idx.rs | ||
| enum-bounds-check-issue-13926.rs | ||
| enum-bounds-check-issue-82871.rs | ||
| enum-bounds-check.rs | ||
| enum-debug-clike.rs | ||
| enum-debug-niche-2.rs | ||
| enum-debug-niche.rs | ||
| enum-debug-tagged.rs | ||
| enum-discriminant-value.rs | ||
| enum-early-otherwise-branch.rs | ||
| enum-match.rs | ||
| enum-u128.rs | ||
| unreachable_enum_default_branch.rs | ||